Conventionally, in making a glass seal in either a D or C sized lithium battery closures (lids), a terminal pin is sealed directly to the margin defining an opening in the closure of the battery. This is accomplished by putting an annular pellet or bead of glass or glass sinter around the terminal pin, placing the closure and pin with the bead around it in a fixture, along with, typically, about 71 other closures, putting the loaded fixture into a furnace or oven and raising the temperature to the melting point of the glass, to permit the glass to bond to the closure and the terminal. This method is slow and expensive. The closure surface has to be clean, the closures occupy a large amount of space, and the energy requirements are high because the closure is large and heavy as compared with the terminal pin and bead or pellet.
Eyelets have been used, in the form of sleeves with a flange extending radially outwardly from one end, and a weld projection formed on the underside of the flange. Terminals were sealed in the sleeve, and the sleeve welded to the battery closure along the weld projection. These eyelets have the advantage of dense loading for treatment in the fusing furnace, but they have two disadvantages. They are expensive and difficult to make, because the weld projection is difficult to form, particularly because all elements of the weld projection (ridge) throughout the 360.degree. compass of the ridge have to lie in a common plane, and the eyelets have to be oriented in a unique direction in the fixturing and in the welding. It has been known, in reefer terminals, for example, to coin a sharp edge on a closure opening to serve as a weld projection, but that does not obviate the need for specific orientation of the terminal, which is in any event in a different environment, in which the characteristics of the materials used (their thicknesses, for example) are quite different from the environment in which the seal of this invention is used.
One of the objects of this invention is to provide a universal seal of the eyelet type which permits dense loading of fixtures, which can be oriented in either of two directions, both for fixturing and for welding, which is easy and cheap to manufacture compared with seals known heretofore, and which facilitates welding by providing a high resistance weld point at a substantially line contact around the entire periphery of the eyelet.
Other objects will become apparent to those skilled in the art in the light of the following description and accompanying drawing.